• (RP) IPA: /ɹɪˈdjuːs/, /ɹɪˈdʒuːs/
• (America) IPA: /ɹɪˈduːs/

reduce (reduces, present participle reducing; past and past participle reduced)

1. (transitive) To bring down the size, quantity, quality, value or intensity of something; to diminish, to lower.

   to reduce weight, speed, heat, expenses, price, personnel etc.

2. (intransitive) To lose weight.
3. (transitive) To bring to an inferior rank; to degrade, to demote.

   to reduce a sergeant to the ranks

   • 1815, Walter Scott, Guy Mannering
   • My father, the eldest son of an ancient but reduced family, left me with little.
   • Nothing so excellent but a man may fasten upon something belonging to it, to reduce it.
   • 1671, John Milton, Samson Agonistes

     ''Having reduced their foe to misery beneath their fears.

   • Hester Prynne was shocked at the condition to which she found the clergyman reduced.
   • 1992, Rudolf M[athias] Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, New York, N.Y.: Columbia University Press, →ISBN, page viii:

     Neither [Jones] […] nor I (in 1966) could conceive of reducing our "science" to the ultimate absurdity of reading Finnish newspapers almost a century and a half old in order to establish "priority."

4. (transitive) To humble; to conquer; to subdue; to capture.

   to reduce a province or a fort

5. (transitive) To bring to an inferior state or condition.

   to reduce a city to ashes

6. (transitive, cooking) To decrease the liquid content of food by boiling much of its water off.
   • 2011, Edward Behr and James MacGuire, The Art of Eating Cookbook: Essential Recipes from the First 25 Years.

     Serve the oxtails with mustard or a sauce made by reducing the soup, if any is left, to a slightly thick sauce.

7. (transitive, chemistry) To add electrons / hydrogen or to remove oxygen.
8. (transitive, metallurgy) To produce metal from ore by removing nonmetallic elements in a smelter.
9. (transitive, mathematics) To simplify an equation or formula without changing its value.
10. (transitive, computer science) To express the solution of a problem in terms of another (known) algorithm.
11. (transitive, logic) To convert a syllogism to a clearer or simpler form
12. (transitive, legal) To convert to written form. (Usage note: this verb almost always appears as "reduce to writing".)

    It is important that all business contracts be reduced to writing.

13. (transitive, medicine) To perform a reduction; to restore a fracture or dislocation to the correct alignment.
14. (transitive, military) To reform a line or column from (a square).
15. (transitive, military) To strike off the payroll.
16. (transitive, Scotland, legal) To annul by legal means.
17. (transitive, obsolete) To translate (a book, document, etc.).

    a book reduced into English

• (to bring down) cut, decrease, lower
• (cooking) inspissate; see also Thesaurus:thicken

• (to bring down) increase

• reducible
• reductase
• reduction
• reductive

• French: réduire
• German: reduzieren, herabsetzen
• Italian: ridurre
• Portuguese: reduzir, diminuir
• Russian: уменьша́ть
• Spanish: reducir

• German: abnehmen
• Italian: dimagrire
• Portuguese: emagrecer
• Russian: худе́ть

• Italian: retrocedere, degradare
• Portuguese: rebaixar
• Russian: понижа́ть

• Italian: ridurre in cattività, sottomettere

• Italian: ridurre
• Portuguese: reduzir

• Italian: ridurre
• Russian: упроща́ть